Mineralogical, physical and chemical analyses of the soils derived from Xiashu loess were carried out. The primary minerals of these soils were found to be mainly composed of light minerals, such as quartz, feldspar a...Mineralogical, physical and chemical analyses of the soils derived from Xiashu loess were carried out. The primary minerals of these soils were found to be mainly composed of light minerals, such as quartz, feldspar and mica, with traces of heavy minerals. Clay minerals, more complicate in composition, were dominated by hydromica, accompanied by smectite, vermiculite, chlorite, kaolinite, 2:1/1:1 randomly interstratified minerals and small amounts of quartz, goethite, lepidocrocite and hematite, Clay minerals were characterized by low crystallinity and fine particle size. In light of the quartz/ feldspars ratio of the 0.01-0.05mm silt fraction, and the clay mineral composition, the freeness of iron oxide, and the silica/ sesquioxide and silica/ alumina ratios in < 0.002mm clay fraction, it is concluded that the weathering intensity of these soils was lower than those of red soil and yellow earth, but higher than that of brown earth, and that the soil allitization, depotassication and hydroxylation of clay minerals increased from west to east and from north to south geographically. However, this general tendency did not coincide exactly with the gradual alteration of the geographic coordinates, and in some places, a reverse tendency also appeared, which could be attributed to the influence of some soil forming factors such as parent material and microtopography.展开更多
Surface chemical properties of soil colloids are the important factor affecting soil fertility and genesis. To provide scientific basis for soil genetic classification, promotion of soil fertility and reasonable ferti...Surface chemical properties of soil colloids are the important factor affecting soil fertility and genesis. To provide scientific basis for soil genetic classification, promotion of soil fertility and reasonable fertilization, the specific surface area and electric charge of soil colloids in relation to clay minerals and organic matter are further discussed on the basis of the results obtained from the studies on surface chemical properties of soil colloids in five main soils of China. Results from the studies show that the effect of clay minerals and organic matter on the surface chemical properties of soil colloids is very complicated because the siloxane surface, hydrated oxide surface and organic matter surface do not exist separately, but they are always mixed together and influenced each other. The understanding of the relationship among clay minerals, organic matter and surface chemical properties of soil colloids depends upon further study of the relevant disciplines of soil science, especially the study on the mechanisms of organo-mineral complexes.展开更多
文摘Mineralogical, physical and chemical analyses of the soils derived from Xiashu loess were carried out. The primary minerals of these soils were found to be mainly composed of light minerals, such as quartz, feldspar and mica, with traces of heavy minerals. Clay minerals, more complicate in composition, were dominated by hydromica, accompanied by smectite, vermiculite, chlorite, kaolinite, 2:1/1:1 randomly interstratified minerals and small amounts of quartz, goethite, lepidocrocite and hematite, Clay minerals were characterized by low crystallinity and fine particle size. In light of the quartz/ feldspars ratio of the 0.01-0.05mm silt fraction, and the clay mineral composition, the freeness of iron oxide, and the silica/ sesquioxide and silica/ alumina ratios in < 0.002mm clay fraction, it is concluded that the weathering intensity of these soils was lower than those of red soil and yellow earth, but higher than that of brown earth, and that the soil allitization, depotassication and hydroxylation of clay minerals increased from west to east and from north to south geographically. However, this general tendency did not coincide exactly with the gradual alteration of the geographic coordinates, and in some places, a reverse tendency also appeared, which could be attributed to the influence of some soil forming factors such as parent material and microtopography.
文摘Surface chemical properties of soil colloids are the important factor affecting soil fertility and genesis. To provide scientific basis for soil genetic classification, promotion of soil fertility and reasonable fertilization, the specific surface area and electric charge of soil colloids in relation to clay minerals and organic matter are further discussed on the basis of the results obtained from the studies on surface chemical properties of soil colloids in five main soils of China. Results from the studies show that the effect of clay minerals and organic matter on the surface chemical properties of soil colloids is very complicated because the siloxane surface, hydrated oxide surface and organic matter surface do not exist separately, but they are always mixed together and influenced each other. The understanding of the relationship among clay minerals, organic matter and surface chemical properties of soil colloids depends upon further study of the relevant disciplines of soil science, especially the study on the mechanisms of organo-mineral complexes.
